Add TypeScript definitions for BackgroundSubtractorMOG2 and BackgroundSubtractor

[Copilot]

• Add TypeScript definitions for BackgroundSubtractor base class
• Add TypeScript definitions for BackgroundSubtractorMOG2
• Add comprehensive test suite in BackgroundSubtractorMOG2.test.ts
• Remove redundant typescript-validation.ts file (covered by test suite)

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[ttt43ttt]

@copilot remove the file test/typescript-validation.ts. the case is covered in test/BackgroundSubtractorMOG2.test.ts already.

[Copilot]

@copilot remove the file test/typescript-validation.ts. the case is covered in test/BackgroundSubtractorMOG2.test.ts already.

Done! Removed test/typescript-validation.ts as the TypeScript validation is already covered in test/BackgroundSubtractorMOG2.test.ts. (commit: will be included in next message)